The speaker module is an important acoustic component of a portable electronic apparatus, and is used for implementing conversion between an electronic signal and a sound signal, and the speaker module is an energy conversion device.
Along with the continuous development of the portable electronic apparatus towards a light, thin and small architecture, the speaker module, as the acoustic component of a portable electronic apparatus, also develops towards the light, thin and small architecture, and therefore, the technicians design more and more speaker modules to have a structure emitting sound at a lateral side of the front cavity. This kind of structure results in that most of sound waves emitted by a speaker unit cannot be directly spread out, but only can be spread out from the sound hole after being reflected by the walls of the front cavity, at which time, however, a standing wave may be formed in the front acoustic cavity after the transmitting waves and reflecting waves of some high frequency sound waves superimposed with each other, which results in the sound waves no longer moving forward, so that the sound waves in this frequency band would not spread out from the sound hole. This results in that the sound pressure amplitude decreases sharply at a high frequency point, and the sensitivity curve of the speaker module generates a deep valley near the high frequency point. As shown in the area of the dotted line in FIG. 9, the sensitivity curve of the speaker module generates a deep valley in the vicinity of the frequency of 10000 Hz, which seriously impacts on the sensitivity of the speaker module in this frequency band, reduces the acoustic performance of the module, and results in performance defects of the module.